[BC] FM History

[Mark Humphrey]

On Mon, Nov 29, 2010 at 7:35 PM, Gary Peterson <kzerocx at rap.midco.net> wrote:

> There is one other characteristic of an electromagnetic wave that might lend
> itself to modulation.  That is polarity.  I remember reading in an amateur
> radio publication (decades ago) that someone was experimenting with
> "polarity modulation."

I remember an article like that too -- Perhaps it first appeared in an
April (fool's) issue of QST?

But this idea would seem to make sense if used for a two-state system
-- so the question for discussion is whether this form of modulation
generates conventional sidebands, or does it occupy an infinitely
narrow bandwidth like a steady unmodulated carrier?  (Not considering
phase noise, etc.)   If the transition between the V and H states is
handled smoothly as a short period of CP, rather than abruptly
switching between the two linear polarizations, should we see an
increase in occupied bandwidth?

If you search Google for "Polarization Shift Keying" you see that this
idea has been used at optical wavelengths.

Mark